Depending on the processed material from each drill must be properly sharpened. To verify the correct angle will help a specially prepared square plate of copper or aluminium with a thickness of 1 mm.
To become operational protractor enough to cut it cut, as shown in the picture: a large cutout at an angle of 120 degrees, the other half is 60 degrees and the surviving corner of a square is 90.
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quickly and Easily you can make gears on a lathe with modular knurling. But the trouble is that this tool is so scarce that not even all the modelers and heard something about it....
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However, it can be made more versatile if the blade is cut, as shown in the figure. This more acute wedge-shaped version of the shovel is easy even in the most dense, parched soil.